Submitting a paper to a journal is a major steppingstone on the path to scientific publication. However, submission does not necessarily (or even usually) mean that work on the manuscript is complete. After submission, most manuscripts undergo a rigorous evaluation process (called peer review) by a panel of experts. The purpose of peer review is to improve the work, maintain standards of quality, provide credibility (to the work and the journal), and to determine the paper's suitability for publication.

There are three basic types of peer review; open review, single-blind review, and double-blind review. In an open review, the identities of both the reviewers and the authors are made known to one another. In a single-blind review, the reviewers are anonymous to the authors. In a double-blind review, both the authors and reviewers are anonymous. The majority of journals in the biological and biomedical sciences employ a single-blind review model. However, the double-blind review model is gaining popularity. Recent research has shown that the double-blind model helps minimize reviewer bias, and levels the playing field for scientists from underrepresented groups.

When a paper is received by a journal, a handling editor screens it for basic quality. If the editor deems the manuscript worthy of consideration, he or she will ask several experts in the field to critically evaluate it. The role of these experts (called ‘peer-reviewers’ or ‘referees’) is to provide constructive feedback to the authors, and tell the editor whether or not the study should be published. The review itself usually consists of responses to a set of specific questions asked by the journal, and a set of comments for the author to consider when revising the manuscript.

What criteria do reviewers use to evaluate a manuscript?

Some journals publish their publication criteria online, but most do not. In the sciences, journals often use a structured question form to request specific feedback from reviewers regarding technical soundness, data quality, originality, significance, and the quality of the writing (including English language use).

Significance and originality

Journals want to publish cutting-edge research that clearly advances scientific knowledge. Therefore, it is not surprising that questions about the paper's significance, or relevance to the field, often appear first on the review form. A journal may ask the reviewer to give his or her opinion about the significance of the research, its novelty, and whether it is clear advance on previous work in the area. Reviewers are often asked to rank the relative importance of the results, given the current state of knowledge in the field (e.g., top 10% of papers, 25%, 50%, lower 50%, lower 25% of papers). Editors weigh reviewer responses to these questions heavily when deciding the fate of a manuscript, so the significance or novelty of the study should be made clear (but not inflated) in your cover letter and abstract, and in the body of your manuscript.

Experimental rigor and data quality

Peer review is a quality control mechanism. A scientific claim must be based on solid conceptual reasoning and good experimental practices before it is published. A journal may ask:

Are the hypotheses being tested clearly stated?

Are the methods and data suitable for the hypotheses being tested?

Are the methods described in sufficient detail for the study to be repeated?

Do you have any animal care or other ethical concerns?

Has the statistical analysis been performed appropriately and rigorously?

Writing quality and manuscript suitability

Scientists work hard to design, carry out and analyze their data with rigor. However, even a solid study with interesting results stands a good chance of being rejected if the writing is weak or suffers from poor English language use. For that reason, it is worth taking the time to have the paper checked by a colleague or professional scientific editing service prior to submission. Common questions about writing quality that may asked by a journal include:

Is the manuscript presented in an intelligible fashion and written in standard English?

Do the title and abstract accurately describe the contents of the article?

Does the introduction clearly state how the study is novel and set out the reasons for, and context of, the study?

Do the conclusions in the Discussion follow from the results?

Is the literature correctly treated, with all relevant references cited?

Is the overall presentation clear and accurate, without wordy or tangential passages, or superfluous tables and figures?

Is the manuscript's length acceptable in the view of its contents?

Is the journal suitable for the manuscript?

Is the work of general interest to the journal’s readership?

Peer review has been criticized for its failure to ensure scientific accuracy. Most reviewers take their role as an objective arbitrar of science seriously, but even the most conscientious researchers may fail to catch an error in the methodology or results, or be unable to detect fraudulent data. Reviewer opinions are also vulnerable to human biases. Nevertheless, most researchers agree that peer review improves the quality of published research, and the review process is likely here to stay. By keeping in mind the criteria used by reviewers to evaluate a manuscript, you can improve the chances that the reviewer will recommend your paper for publication earlier.